The present invention is in the field of release liners used for carrying seal labels and other adhesive coated components used on electronic components.
At least three properties are desired in a release liner. The liner may have anti-static properties, it may have some indication as to which side of the tape the seal labels should be applied and the liner needs to have a release layer that is clean. The visual indication as to which side of the liner is which is very important and can potentially save a company from making a costly mistake in applying the seal labels to the wrong side of the tape. The cleanliness of the liner is imperative to creating a product with very few contaminants. The major contamination test technique for hard disk drive and semiconductor applications is Dynamic Head Space Gas Chromatograhpy/Mass Spectroscopy (DHS-GC-MS). It is used to identify outgasable components in the ng/cm2 level. Another test that is run on release liners is a solvent extraction test. In a solvent extraction test the extract is analyzed by Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR). The amount of siloxane extracted from the liner is then reported in ng/cm2.
The present invention includes an improved purified liner and a method for its preparation. The improved method of the present invention allows for the removal of unwanted non-bonded components in the release coat.
The present invention includes a purified flexible liner material for supporting a pressure sensitive product comprising the following layers:
a) a support layer having a first and a second side;
b) a first adhesive disposed on the first side of said support layer;
c) a first release coating disposed on the first adhesive;
d) a first polymer film layer disposed on the first release coating;
e) a second adhesive disposed on the second side of said support layer;
f) a second release coating disposed on the second adhesive; and
g) a second polymer film layer disposed on the second release coating.
Included in the present invention is a method of making a purified flexible liner material comprising the steps of:
a) coating a release coating on a polymer film;
b) subjecting said polymer film to at least one purification step selected from the group consisting of vacuum deposition of a metal, sputtering a metal and solvent wash, to substantially remove non-bonded impurities; and
c) coating the purified polymer film with an adhesive.
By exposing the release liner to a vacuum or to heat the outgasable components are removed by evaporation. The solvent wash process is used to remove unwanted non-bonded moieties that are present in an industrial release coat.
Also included in the present invention is a method of making a purified flexible liner material for supporting a pressure sensitive product comprising the steps of:
a) coating a support layer, composed of a first and second side, with an adhesive, on the first side;
b) coating the first adhesive with a first release coating;
c) coating the first release coating with a first polymer film layer;
d) coating a second release coating, composed of a first and second side, with a second polymer film layer, on the first side;
e) coating the second release coating with a second adhesive on the second side; and
f) laminating the second adhesive layer to the second side of the support layer of step a) above, wherein at least one polymer film layer is treated with at least one method selected from vacuum deposition of a metal, sputtering a metal and solvent wash, to substantially remove non-bonded impurities.